The chicken eye was previously found to have little off-axis astigmatism which is not explained by its special corneal shape but rather by the optical properties of the crystalline lens. To learn more about lens design, we studied off-axis astigmatism in the chicken lens in situ and compared it to a glass lens of similar power but with homogenous refractive index. After euthanasia, enucleated eye balls were cut in the equatorial plane right behind the scleral ossicles. The anterior segment was placed in a water-filled chamber...

PURPOSE: To study rule similarity (isorule or anisorule) and symmetry patterns of axes (direct and mirror) in bilateral astigmatism. METHODS: Six years of data were collected from four ophthalmology clinics in Tehran. After applying the exclusion criteria (having eye disease or history of ocular surgery), final analyses were performed on data of 160 608 cases whose mean age was 39.2 ± 15.4 years (10-80 years) and 53.7% female. All subjects had autorefraction, retinoscopy, and subjective refraction data...

PURPOSE: A continuous set of personalized designs (design space) for progressive addition lenses (PALs) is investigated. The main goals are (1) to study how the subjects' perception of a personalized design depends on its position in the design space and (2) to compare the performance of personalized PALs to a conventional PAL with a fixed design. METHODS: In a double-blind study, 51 subjects compared Rodenstock Impression FreeSign 3, which is a family of PALs with a continuously controllable personalized design, and Rodenstock Progressiv Life Free, which is a conventional PAL with a single fixed design...

OBJECTIVE: To investigate the influence of creating a flap on the postoperative optical quality of the cornea in terms of predicted corneal curvature and Seidel aberrations after 2 modalities of femtosecond assisted corneal lenticule extraction laser for the correction of myopia and myopic astigmatism: The flapless procedure small incision lenticular extraction (SMILE) and the flap-based femtosecond lenticular extraction (FLEx). METHODS: The study is a prospective consecutive non-randomised comparative interventional case series including 64 eyes with myopic or myopic astigmatism refractive errors...

PURPOSE: To detect corneal inflammation and apoptosis induced after small incision lenticule extraction (SMILE) at different refractive corrections for moderate to high values of myopia. METHODS: Fifty patients (50 eyes) suffering from medium to high myopia (spherical equivalent refraction from -3.75 to -10.00 diopters (D) with refractive astigmatism under -0.75 D) underwent SMILE in order to correct myopic error. In vivo evaluation was done by corneal confocal microscopy (IVCM) and ex vivo by immunohistochemistry...

CONTEXT: Surgical outcome of retropupillary fixation of iris claw lens. AIMS: To evaluate the various indications, intra and post-operative complications, and visual outcome of retropupillary fixation of iris claw lens in aphakic eyes. SETTINGS AND DESIGN: The study design is a retrospective study at a tertiary eye care center. METHODS: Review of medical records of 61 aphakic eyes of 61 patients, who were rehabilitated with retropupillary fixation of an iris claw lens, with a follow-up duration of at least 1 year...

Purpose: We compared the anterior segment characteristics of congenital cataract (CC) patients with lens opacities in different locations and proposed a modified, simple CC category system. Methods: Cataractous eyes of CC patients were classified into four groups based on the locations of lens opacities shown in slit-lamp examinations and by a 3-dimensional anterior segment imaging system as follows: total, anterior, interior, and posterior cataracts. The mean keratometry value, corneal astigmatism (CA), central corneal thickness (CCT), and anterior chamber depth (ACD) of eyes in different groups were compared...

PURPOSE: This study aims to address the clinical performance of a large diameter rigid gas permeable lens (LRGP) in a group of subjects with low-to-moderate (0.75-2.75 D) refractive astigmatism. An additional goal was to determine whether soft toric or LRGP contact lenses performed better objectively in the correction of astigmatism and to determine which modality is preferred by subjects. METHODS: This was a multisite prospective cross-over clinical study. Ten asymptomatic contact lens wearers per site (four university clinics) were recruited and randomly assigned to group A or group B...

Infantile hemangiomas are the most common vascular neoplasm that present in infancy, with more than half affecting the head and neck region. Periocularly, hemangiomas may be complicated by visual loss through induction of strabismal, deprivational, or anisometropic astigmatism. We report a case of a 5-year-old girl who presented with orbital hemangioma with potential risk of visual loss who had excellent response to propranolol.

Importance: Patient-reported outcomes should be collected using validated questionnaires prior to and following laser in situ keratomileusis (LASIK) surgery. Objective: To report the frequency of patient-reported visual symptoms, dry eye symptoms, satisfaction with vision, and satisfaction with LASIK surgery in the Patient-Reported Outcomes With LASIK (PROWL) studies. Design, Setting, and Participants: The PROWL-1 and PROWL-2 studies were prospective, observational studies conducted from September 13, 2011, to June 27, 2014...

The aim of this study was to evaluate primitively whether the extent and component of astigmatism influences regression in degree of spherical (DS) and the best corrected visual acuity (BCVA) of children with hyperopia of +5.00 diopters (D) or greater. Children were screened from the outpatient refraction database in the Wenling No. 1 People's Hospital in Zhejiang province and in Eye & ENT Hospital of Fudan University between June 2005 and December 2015. Eligible eyes were divided into three groups according to the extent of astigmatism: group of astigmatism ≤ -2 D of cylinder, group without astigmatism or with astigmatism ≥ -0...

OBJECTIVE: To evaluate the efficacy and safety of transepithelial (TE) collagen cross-linking (CXL) in patients with progressive keratoconus (KC). METHODS: This Quasi Experimental Study was conducted at PNS Shifa Naval Hospital, Karachi from June 2015 to June 2016. Sixty eyes of 32 patients who underwent TE CXL for progressive KC from June 2015 to June 2016 were analysed to ascertain efficacy and safety of TE CXL procedure. Statistical analysis of the data was done using SPSS version 17...

Compact folded imaging systems often require freeform surfaces to correct astigmatic and other off-axis aberrations. However, aberration theory for non-rotational symmetric systems is quite complex and it is especially hard to quantify individual surface aberration contributions. In this paper we develop a matrix method based on the propagation of a differential ray pair, which allows determining the aberration contribution of each individual surface for any ray. We can mathematically prove that the sum of the aberrations is identical to the exact ray-tracing result at the image plane...